It looks to be an amazing service, but from what I’ve read there are no invites. You’re comparing it to what they did with Gmail where access to the 17 year long beta was gained in the beginning through invites from people already signed up.

As of right now I don’t even think its open to the public, and if it is, its a very select few. Invites only come from Google and you need to sign up to throw your name in the hat.